MicroPET: tomografía por emisión de positrones para animales de laboratorio / MicroPET: Positron emission tomography for laboratory animals

Resumen: El tomógrafo por emisión de positrones (PET, por sus siglas en inglés [positron emission tomography]) es una poderosa herramienta no invasiva para el diagnóstico clínico e investigación in vivo por medio de imágenes empleada en humanos y animales de laboratorio. Se han desarrollado equipos exclusivos para los diversos modelos animales con los beneficios de esta técnica para el estudio de diferentes enfermedades.

Abstract: The positron emission tomography , PET scan (Positron Emission Tomography) is a powerful noninvasive tool for clinical diagnosis and research in vivo by means of images used in humans and laboratory animals. We have developed exclusive equipment for the various animal models with the benefits of this technique for the study of different diseases.

(18)FDG PET/CT en linfoma primario de mama y cáncer de mama / (18)FDG PET/CT imaging in primary breast lymphoma and breast cancer

BACKGROUND: Of women between 15 and 29 years of age, 13.6% will die from breast cancer. For women between 30 and 64 years of age, 19% will die from breast cancer. METHODS: We studied 1728 oncological patients and 295 patients were included, 293 with breast cancer (17%) and two patients with primary breast lymphoma (0.1%). RESULTS: There were 98% females and 2% males. SUVmax for the primary tumor was 4.2 +/- 2.6 SD. Mean SUVmax for patients with primary breast lymphoma were 3.2 and 1.4. Sites of metastases were lymph nodes in the neck (4.4% SUVmax 2.7), internal mammary lymph nodes (5% SUVmax 5.3), mediastinum (8.3% SUVmax 5.0), retroperitoneal (6 % SUVmax 5.4), ipsilateral axilla (94% SUVmax 4.5), contralateral axilla (4.4% SUVmax 2.8), pectoral muscle (10.2% SUVmax 2.6), pleura (4.4% SUVmax 3.9), lung (32.3% SUVmax 2.9), liver (19.1% SUVmax 4.5), bone (36.7%), adrenal gland (4.4% SUVmax 2.4), brain (4.4%), spleen and contralateral breast, one case each. One patient presented thymic hyperplasia after chemotherapy. Mean SUVmax for blastic lesions was 5.4 +/- 2.9 SD, for lytic lesions it was 6.7 +/- 2.4 SD and for lesions not apparent on the CT it was 4.6 +/- 2.4 SD. The incidence of a second primary was 4.7%, 2.1% ovarian, 1.4% lung, 0.3% lymphoma, 0.3% endometrium, 0.3% pancreas and 0.3% thyroid. CONCLUSIONS: Mean SUVmax for the primary tumor was similar to that reported in the literature. Values for metastatic bone lesions are higher in this study. Inclusion of PET/CT in the followup of breast lesions is cost efficient.

Captaciones fisiológicas y variantes normales en el estudio PET/CT con (18)FDG / Normal variants and frequent pitfalls with (18)FDG PET/CT study

BACKGROUND: Fluordeoxyglucose ((18)FDG) is the most common radiotracer used for PET/CT studies. It enters the cell because of the glucose transporter proteins (GLUTs): 1) erythrocytic membrane, skeletal muscle, lymphocytes, ovaries, breast; 2) pancreas, retina, erythrocytes; 3) adipocytes, ovaries, testis; 4) skeletal muscle, adipocytes, ovaries, myocardium; 5) breast, small intestine, testis, kidney, erythrocytes; 6) spleen, leucocytes, brain; 7) liver; 8) testis, brain; 9) liver, kidney; 10) liver, pancreas; 11) heart, muscle; 12) heart, prostate; 13) brain. We undertook this study to expand the knowledge about physiological uptake. Physiological uptake of (18)FDG was in brain, Waldeyer ring (adenoids, palatine tonsils, lingual tonsils), salivary glands (parotids, submandibular), tongue, vocal cords, cricoarythenoid muscle, thyroid, brown fat (supraclavicular, mediastinal, neck, pericardial fat, around kidney, around great vessels in the thorax, subdiaphragmatic, intercostals, paravertebral), myocardium, breast, thymus, contractive muscles, liver, spleen (similar to the liver), stomach, intestine, kidneys, bladder, uterus, ovaries, testes, bone marrow, esophagus, and atherosclerotic inflammatory plaque. DISCUSSION: False positives were as follows: pneumoniae, tuberculosis, sarcoidosis, cryptococcosis, thrombosis, bronchitis, costochondritis, radiation pneumonitis, misregistration for respiratory movements, catheters, thyroid and adrenal adenomas, osteophytes, fractures, abscess, foreign body, surgical wounds, ostomies, prosthesis, degenerative joint diseases, osteomyelitis, amyloidosis, pancreatitis, myositis, gastritis, colitis, herpes zoster. (18)FDG should be injected 4-6 h after insulin administration because it will be concentrated in the muscles. The brown fat raises its uptake 50% in late images. CONCLUSIONS: It is vital to know the most frequent sites of physiological uptake in the (18)FDG PET/CT studies to identify those regions that occasionally present hypermetabolism but that are not related to neoplastic tumors. This must be taken into consideration in the evaluation of PET/CT studies.